Add alerts to PWMDutyCycleEncoder and SparkMax

swervelib/encoders/PWMDutyCycleEncoderSwerve.java

@@ -26,6 +26,10 @@ public class PWMDutyCycleEncoderSwerve extends SwerveAbsoluteEncoder
    * An {@link Alert}  for if the encoder cannot report accurate velocities.
    */
   private       Alert            inaccurateVelocities;
+    /**
+   * An {@link Alert}  for if the encoder is disconnected.
+   */
+  private       Alert            disconnected;
 
   /**
    * Constructor for the PWM duty cycle encoder.
@@ -39,6 +43,10 @@ public class PWMDutyCycleEncoderSwerve extends SwerveAbsoluteEncoder
         "Encoders",
         "The PWM Duty Cycle encoder may not report accurate velocities!",
         Alert.AlertType.WARNING_TRACE);
+    inaccurateVelocities = new Alert(
+        "Encoders",
+        "The swerve encoder on port " + pin + "is disconnected!",
+        Alert.AlertType.ERROR_TRACE);
 
   }
 
@@ -61,6 +69,7 @@ public class PWMDutyCycleEncoderSwerve extends SwerveAbsoluteEncoder
   @Override
   public double getAbsolutePosition()
   {
+    disconnected.set(!encoder.isConnected());
     return (isInverted ? -1.0 : 1.0) * encoder.getAbsolutePosition() * 360;
   }
 
@@ -83,6 +92,7 @@ public class PWMDutyCycleEncoderSwerve extends SwerveAbsoluteEncoder
   @Override
   public double getVelocity()
   {
+    disconnected.set(!encoder.isConnected());
     inaccurateVelocities.set(true);
     return encoder.get();
   }